Light-emitting device and manufacturing method thereof

ABSTRACT

The present invention provides a light-emitting device and a manufacturing method thereof. The light-emitting device includes: a heat dissipation layer ( 2 ), a buffer layer ( 4 ) formed on the heat dissipation layer ( 2 ), and a light emission unit ( 6 ) formed on the buffer layer ( 4 ). The heat dissipation layer ( 2 ) is made of graphene. The manufacturing method of a light-emitting device according to the present invention makes use of a graphene-made heat dissipation layer to effectively dissipate away heat emitting from the emissive layer of the light emission unit so as to effectively reduce the temperature of the light-emitting device and extend the service life of the light-emitting device. Particularly, when the light-emitting device is a light-emitting diode, the emissive layer thereof is a quantum dot emissive layer for effectively improving color saturation of the light-emitting diode and enhancing color displaying performance of the light-emitting diode.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light-emitting device, and inparticular to a light-emitting device that has excellent heatdissipation performance.

2. The Related Arts

Light-emitting diodes (LEDs) and organic electroluminescent displays(OELDs) are two commonly used light-emitting devices at present.

The light-emitting diode comprises a semiconductor P-N junctionstructure to cause injections of minority charge carriers (electrons orholes) and to give of light through re-combination of the minoritycharge carriers. In other words, if a positive voltage is applied to aspecific element of the semiconductor, the electrons and the holes, whenpassing through an intermediate structure between an anode and acathode, re-combine with each other. Such a state has a energy less thanthat of the state where the electrons and the holes are separate fromeach other and thus, emission of light results due to the difference ofenergy at this moment.

The organic electroluminescence display comprises thin coatings oforganic materials on a glass substrate, so that when an electricalcurrently is conduct to pass, the organic coatings get luminous.

A currently available white LED generally comprises a blue die with anexternal package of yellow YAG fluorescent powder so as to result in acombination of lights to generate a white light; however, the colorrendering index thereof is low. Further, the base layer of an LED oftencomprises sapphire, which has relatively low thermal conductivity(generally less than 50 W/m.K) and this leads to poor heat dissipationof the LED, thus affecting the luminous efficiency and lifespan of theLED.

Similarly, the glass substrate of the OLED is also of thermalconductivity that is not high, similarly suffering the issue of heatdissipation.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a light-emitting devicethat has excellent heat dissipation performance, an extended life ofservice, and improved color displaying performance.

Another object of the present invention is to provide a manufacturingmethod of a light-emitting device, which has a simple process and whichmakes a light-emitting device having excellent heat dissipationperformance and an extended life of service, and the light-emittingdevice also showing improved color displaying performance.

To achieve the objects, the present invention provides a light-emittingdevice, which comprises: a heat dissipation layer, a buffer layer formedon the heat dissipation layer, and a light emission unit formed on thebuffer layer. The heat dissipation layer is made of graphene.

The light emission unit comprises: an electron transporting layer formedon the buffer layer, an emissive layer formed on the electrontransporting layer, an N type ohmic contact electrode formed on theelectron transporting layer and located at one side of the emissivelayer, a hole transporting layer formed on the emissive layer, atransparent conductive layer formed on the hole transporting layer, anda P type ohmic contact electrode formed on the transparent conductivelayer.

The emissive layer is a quantum dot emissive layer.

The transparent conductive layer is an indium tin oxides layer.

The light emission unit comprises: an anode formed on a buffer layer, ahole transporting layer formed on the anode, an organic emissive layerformed on the hole transporting layer, an electron transporting layerformed on the organic emissive layer, and a cathode formed on theelectron transporting layer.

A manufacturing method of a light-emitting device comprises thefollowing steps:

(1) providing a base, wherein the base comprises a heat dissipationlayer and the heat dissipation layer is made of graphene;

(2) forming a buffer layer on the heat dissipation layer; and

(3) forming a light emission unit on the buffer layer.

The light emission unit comprises: an electron transporting layer formedon the buffer layer, an emissive layer formed on the electrontransporting layer, an N type ohmic contact electrode formed on theelectron transporting layer and located at one side of the emissivelayer, a hole transporting layer formed on the emissive layer, atransparent conductive layer formed on the hole transporting layer, anda P type ohmic contact electrode formed on the transparent conductivelayer.

The emissive layer is a quantum dot emissive layer.

The transparent conductive layer is an indium tin oxides layer.

The light emission unit comprises: an anode formed on a buffer layer, ahole transporting layer formed on the anode, an organic emissive layerformed on the hole transporting layer, an electron transporting layerformed on the organic emissive layer, and a cathode formed on theelectron transporting layer.

A manufacturing method of a light-emitting device comprises thefollowing steps:

(1) providing a base, wherein the base comprises a heat dissipationlayer and the heat dissipation layer is made of graphene;

(2) forming a buffer layer on the heat dissipation layer; and

(3) forming a light emission unit on the buffer layer;

wherein the light emission unit comprises: an electron transportinglayer formed on the buffer layer, an emissive layer formed on theelectron transporting layer, an N type ohmic contact electrode formed onthe electron transporting layer and located at one side of the emissivelayer, a hole transporting layer formed on the emissive layer, atransparent conductive layer formed on the hole transporting layer, anda P type ohmic contact electrode formed on the transparent conductivelayer.

The emissive layer is a quantum dot emissive layer.

The transparent conductive layer is an indium tin oxides layer.

The efficacy of the present invention is that the present inventionprovides a light-emitting device and a manufacturing method thereof, inwhich a heat dissipation layer is made of graphene to effectivelydissipate away the heat emitting from the emissive layer so as toeffectively reduce the temperature of the light-emitting device andextend the service life of the light-emitting device. Particularly, whenthe light-emitting device is a light-emitting diode, the emissive layerthereof is a quantum dot emissive layer for effectively improving colorsaturation of the light-emitting diode and enhancing color displayingperformance of the light-emitting diode.

For better understanding of the features and technical contents of thepresent invention, reference will be made to the following detaileddescription of the present invention and the attached drawings. However,the drawings are provided for the purposes of reference and illustrationand are not intended to impose undue limitations to the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The technical solution, as well as beneficial advantages, of the presentinvention will be apparent from the following detailed description of anembodiment of the present invention, with reference to the attacheddrawings. In the drawings:

FIG. 1 is a schematic view showing the structure of a first embodimentof a light-emitting device according to the present invention;

FIG. 2 is a schematic plan view showing the structure of a firstembodiment of a light-emitting device according to the presentinvention; and

FIG. 3 is a flow chart illustrating a manufacturing method of alight-emitting device according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

To further expound the technical solution adopted in the presentinvention and the advantages thereof, a detailed description is given toa preferred embodiment of the present invention and the attacheddrawings.

Referring to FIG. 1, the present invention provides a light-emittingdevice, which comprises: a heat dissipation layer 2, a buffer layer 4formed on the heat dissipation layer 2, and a light emission unit 6formed on the buffer layer 4. The heat dissipation layer 2 is made ofgraphene.

Graphene has thermal conductivity of 4000-6000 W/m.K, which caneffectively transfers heat emitting from the light emission unit 6 tothe surroundings so as to effectively reduce the temperature of thelight-emitting device and extend the service life of the light-emittingdevice.

Referring to FIG. 1, in the instant embodiment, the light-emittingdevice comprises a light-emitting diode (LED) and the light emissionunit 6 comprises: an electron transporting layer 62 formed on the bufferlayer 4, an emissive layer 64 formed on the electron transporting layer62, an N type ohmic contact electrode 66 formed on the electrontransporting layer 62 and located at one side of the emissive layer 64,a hole transporting layer 67 formed on the emissive layer 64, atransparent conductive layer 68 formed on the hole transporting layer67, and a P type ohmic contact electrode 69 formed on the transparentconductive layer 68.

In the instant embodiment, the emissive layer 64 is a quantum dotemissive layer, which effectively improves color saturation of thelight-emitting diode and enhance color displaying performance of thelight-emitting diode.

The transparent conductive layer 68 is an ITO (Indium Tin Oxides) layer.

Referring to FIG. 2, in another embodiment, the light-emitting device isan organic electroluminescence display (OLED), which comprises a lightemission unit 6′ comprising: an anode 602 formed on a buffer layer 4, ahole transporting layer 604 formed on the anode 602, an organic emissivelayer 606 formed on the hole transporting layer 604, an electrontransporting layer 608 formed on the organic emissive layer 606, and acathode 609 formed on the electron transporting layer 608.

Referring to FIG. 3, with additional reference to FIGS. 1 and 2, amanufacturing method of a light-emitting device comprises the followingsteps:

Step 101: providing a base, wherein the base comprises a heatdissipation layer 2 and the heat dissipation layer 2 is made ofgraphene.

Graphene has thermal conductivity of 4000-6000 W/m.K, which caneffectively transfers heat emitting from the light-emitting device tothe surroundings so as to effectively reduce the temperature of thelight-emitting device and extend the service life of the light-emittingdevice.

Step 102: forming a buffer layer 4 on the heat dissipation layer 2.

Step 103: forming a light emission unit 6 on the buffer layer 4.

In the instant embodiment, the light-emitting device comprises alight-emitting diode (LED) and the light emission unit 6 comprises: anelectron transporting layer 62 formed on the buffer layer 4, an emissivelayer 64 formed on the electron transporting layer 62, an N type ohmiccontact electrode 66 formed on the electron transporting layer 62 andlocated at one side of the emissive layer 64, a hole transporting layer67 formed on the emissive layer 64, a transparent conductive layer 68formed on the hole transporting layer 67, and a P type ohmic contactelectrode 69 formed on the transparent conductive layer 68.

The emissive layer 64 is a quantum dot emissive layer, which effectivelyimproves color saturation of the light-emitting diode and enhance colordisplaying performance of the light-emitting diode. The transparentconductive layer 68 is an ITO (Indium Tin Oxides) layer.

In another embodiment, the light-emitting device is an organicelectroluminescence display (OLED), which comprises a light emissionunit 6′ comprising: an anode 602 formed on a buffer layer 4, a holetransporting layer 604 formed on the anode 602, an organic emissivelayer 606 formed on the hole transporting layer 604, an electrontransporting layer 608 formed on the organic emissive layer 606, and acathode 609 formed on the electron transporting layer 608.

In summary, the present invention provides a light-emitting device and amanufacturing method thereof, in which a heat dissipation layer is madeof graphene to effectively dissipate away the heat emitting from theemissive layer so as to effectively reduce the temperature of thelight-emitting device and extend the service life of the light-emittingdevice. Particularly, when the light-emitting device is a light-emittingdiode, the emissive layer thereof is a quantum dot emissive layer foreffectively improving color saturation of the light-emitting diode andenhancing color displaying performance of the light-emitting diode.

Based on the description given above, those having ordinary skills ofthe art may easily contemplate various changes and modifications of thetechnical solution and technical ideas of the present invention and allthese changes and modifications are considered within the protectionscope of right for the present invention.

What is claimed is:
 1. A light-emitting device, comprising: a heatdissipation layer, a buffer layer formed on the heat dissipation layer,and a light emission unit formed on the buffer layer, the heatdissipation layer being made of graphene.
 2. The light-emitting deviceas claimed in claim 1, wherein the light emission unit comprises: anelectron transporting layer formed on the buffer layer, an emissivelayer formed on the electron transporting layer, an N type ohmic contactelectrode formed on the electron transporting layer and located at oneside of the emissive layer, a hole transporting layer formed on theemissive layer, a transparent conductive layer formed on the holetransporting layer, and a P type ohmic contact electrode formed on thetransparent conductive layer.
 3. The light-emitting device as claimed inclaim 2, wherein the emissive layer is a quantum dot emissive layer. 4.The light-emitting device as claimed in claim 2, wherein the transparentconductive layer is an indium tin oxides layer.
 5. The light-emittingdevice as claimed in claim 1, wherein the light emission unit comprises:an anode formed on a buffer layer, a hole transporting layer formed onthe anode, an organic emissive layer formed on the hole transportinglayer, an electron transporting layer formed on the organic emissivelayer, and a cathode formed on the electron transporting layer.
 6. Amanufacturing method of a light-emitting device, comprising thefollowing steps: (1) providing a base, wherein the base comprises a heatdissipation layer and the heat dissipation layer is made of graphene;(2) forming a buffer layer on the heat dissipation layer; and (3)forming a light emission unit on the buffer layer.
 7. The manufacturingmethod of a light-emitting device as claimed in claim 6, wherein thelight emission unit comprises: an electron transporting layer formed onthe buffer layer, an emissive layer formed on the electron transportinglayer, an N type ohmic contact electrode formed on the electrontransporting layer and located at one side of the emissive layer, a holetransporting layer formed on the emissive layer, a transparentconductive layer formed on the hole transporting layer, and a P typeohmic contact electrode formed on the transparent conductive layer. 8.The manufacturing method of a light-emitting device as claimed in claim7, wherein the emissive layer is a quantum dot emissive layer.
 9. Themanufacturing method of a light-emitting device as claimed in claim 7,wherein the transparent conductive layer is an indium tin oxides layer.10. The manufacturing method of a light-emitting device as claimed inclaim 6, wherein the light emission unit comprises: an anode formed on abuffer layer, a hole transporting layer formed on the anode, an organicemissive layer formed on the hole transporting layer, an electrontransporting layer formed on the organic emissive layer, and a cathodeformed on the electron transporting layer.
 11. A manufacturing method ofa light-emitting device, comprising the following steps: (1) providing abase, wherein the base comprises a heat dissipation layer and the heatdissipation layer is made of graphene; (2) forming a buffer layer on theheat dissipation layer; and (3) forming a light emission unit on thebuffer layer; wherein the light emission unit comprises: an electrontransporting layer formed on the buffer layer, an emissive layer formedon the electron transporting layer, an N type ohmic contact electrodeformed on the electron transporting layer and located at one side of theemissive layer, a hole transporting layer formed on the emissive layer,a transparent conductive layer formed on the hole transporting layer,and a P type ohmic contact electrode formed on the transparentconductive layer.
 12. The manufacturing method of a light-emittingdevice as claimed in claim 11, wherein the emissive layer is a quantumdot emissive layer.
 13. The manufacturing method of a light-emittingdevice as claimed in claim 11, wherein the transparent conductive layeris an indium tin oxides layer.